The Corner Poggendorff

Perception ◽  
1988 ◽  
Vol 17 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Ernest Greene
Keyword(s):  
Relative Position ◽  
Poggendorff Illusion ◽  
Oblique Line ◽  
The Other ◽  
Line Segments ◽  
Poggendorff Effect

With the classic Poggendorff illusion a set of parallel ‘induction lines’ will cause a set of oblique line segments to look misaligned even though they are collinear. A different kind of misalignment can be produced by placing the induction lines so that they form a corner. Under these conditions the obliques will appear to be angled slightly, one relative to the other. The effects are small, but can be seen and reliably reported by a group of naive subjects. The influence of the induction lines drops sharply as their relative position is moved from parallel to orthogonal, but there is a small residual influence which may be called the corner Poggendorff effect.

The Poggendorff Illusion with Subjective Contours

1977 ◽  
Vol 29 (2) ◽  
pp. 219-226 ◽  
Author(s):  
R. H. Day ◽  
R. G. Dickinson ◽  
M. K. Jory
Keyword(s):  
Poggendorff Illusion ◽  
Oblique Line ◽  
The Other ◽  
Misalignment Effect

Gregory (1972) has claimed that the Poggendorff misalignment effect occurs when the collinear obliques are separated by subjective rather than real contours. He used two figures to demonstrate this variant of the illusion. Two experiments to test the claim are reported. The first showed that apparent misalignment in one of the two original figures is no greater than that with two obliques alone (the oblique line effect), but misalignment in the other is greater than with two oblique lines and than with a control without subjective contours. The second experiment showed that apparent misalignment in the second figure was less than in two control figures without subjective contours. Since this reduced effect was probably due to the nature of the intersection between the oblique and a semi-circular element, the role of subjective contours remains unsettled.

The development of body and organ shape

BMC Zoology ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ansa E. Cobham ◽  
Christen K. Mirth
Keyword(s):  
Relative Position ◽  
Body Shape ◽  
Single Cells ◽  
The Other ◽  
Geometric Features ◽  
Main Text ◽  
Size Characterization ◽  
Organ Shape ◽  
The Many

Abstract Background Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body. Main text Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics. Conclusion In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.

The Optical-Geometrical Illusion “Corner Poggendorff” Re-Examined

1993 ◽  
Vol 76 (3_suppl) ◽  
pp. 1283-1286 ◽  
Author(s):  
Giovanni Bruno Vicario ◽  
Elena Zambianchi
Keyword(s):  
The Other ◽  
Geometrical Illusion ◽  
Parallel Path ◽  
Poggendorff Effect ◽  
General Conditions

In 1988 Greene noted, if a straight pair of obliques are drawn outside of two orthogonal lines, the segments appear to be angled slightly one relative to the other. This illusion, designated as “corner Poggendorff,” is different from the Poggendorff effect (the two obliques seem to lie on a parallel path). The results of the present experiments ( N = 76 students) suggest that the general conditions for the corner Poggendorff are similar to those for the Judd illusion.

Distribution of Pyrenoids Among Some Brown Algae

1966 ◽  
Vol 1 (4) ◽  
pp. 449-454
Author(s):  
L. V. EVANS
Keyword(s):  
Electron Microscope ◽  
Relative Position ◽  
Brown Algae ◽  
Light Microscope ◽  
The Other ◽  
Taxonomic Character ◽  
The Subject

The distribution of pyrenoids among some orders of the brown algae has been investigated with the electron microscope and a report on their occurrence is given, with particular reference to the results obtained with the light microscope by Simon (1954). Some illustrated detail of the structure of the pyrenoids and of the chromatophores is included. Pyrenoids were found to be present in the representatives examined of the Ectocarpales, Sphacelariales, Scytosiphonales and Dictyosiphonales. Excepting the Sphacelariales, this is in agreement with the results of Simon. Pyrenoids were found to be definitely absent in all members of the Dictyotales and Laminariales examined, and disagreement is expressed with Bouck (1965) who reported their presence in Chorda filum, a member of the latter order. The situation in the Fucales is the subject of another communication elsewhere. The presence or absence of pyrenoids is regarded as an additional taxonomic character of possible phyletic use when more is known. The results are discussed from the standpoint of their possible value in assessing the relative position of the Phaeophyceae as a whole. Brown algal lamellations are composed of three, or occasionally four, parallel thylakoids which do not cohere and are not aggregated into stacks. This is thought to be more primitive than the condition in some of the other groups of the Chromophyta where there is adherence of thylakoids into stacks of two or three members as, for example, in the Haptophyceae, Xanthophyceae and Chrysophyceae. The Phaeophyceae are, however, regarded as much less primitive than the Rhodophyceae, where the widely spaced parallel thylakoids are arranged singly.

The Poggendorff Illusion and Apparent Interparallel Extents

Perception ◽  
1992 ◽  
Vol 21 (5) ◽  
pp. 599-610 ◽  
Author(s):  
Ross H Day ◽  
Erica J Stecher ◽  
Andrea L Parker
Keyword(s):  
Poggendorff Illusion ◽  
Parallel Line ◽  
Significant Error ◽  
The Other ◽  
Misalignment Effect ◽  
The Third ◽  
Horizontal Extent ◽  
Lyer Illusion

An explanation of the Poggendorff misalignment effect in terms of apparent contraction of interparallel extent resulting from the Müller-Lyer illusion was tested in three experiments. Three of the eight stimulus figures had oblique transversals outside the parallels in the usual way, three had them inside, and two were controls consisting of the transversals only. Müller-Lyer forms were differently delineated between the parallels for the inside-transversal and outside-transversal figures, and were not delineated in the control figures. In the first experiment apparent misalignment occurred in four of the six parallel-line figures and in neither of the controls. In the second experiment oblique extent between the parallels was underestimated in six of the eight figures and right-angle extent was overestimated in all of them. The results of the third experiment showed that right-angle (horizontal) extent between the parallels without transversals is estimated without significant error. The data from the three experiments do not support the interparallel-extent explanation of apparent misalignment. Instead, the results are interpreted in terms of independent perceptual compromises, one involving alignment of the transversals and the other the distance between them.

A Seventeenth-Century Polyglot Grammar

1979 ◽  
Vol 6 (1) ◽  
pp. 1-14
Author(s):  
Bertil Sundby
Keyword(s):  
Seventeenth Century ◽  
Word Order ◽  
Relative Position ◽  
The Other ◽  
Practical Skill ◽  
Language Philosophy ◽  
Parts Of Speech ◽  
Weak Points ◽  
And Gender ◽  
Parallel Texts

Summary Jean Sterpin was a Frenchman who flourished in Copenhagen in the mid-nth century. His claim to recognition rests on his polyglot grammar, Institu-tiones Glotticæ (c. l668). Sterpin was acquainted with the language philosophy of Comenius, whose Janua Linguarum (1631) had set the pattern of the polyglot genre, with the work of Nathanael Duёz (fl. 1640–78), the polyglot lexicographer-grammarian, and with Erik Eriksen Pontoppidan’s Grammatica Danica (1668). The way in which Sterpin tackles the problem of teaching the grammar of three languages (French, English and Danish) and proficiency in four (incl. Latin) is superior to the schemes employed by Beyer (1661), Howell (1662), Smith (1674), and Colsoni (1688). His method of presentation is a skilful combination of typographic variation, Vertical alternation’, and the use of parallel texts. More important still, his description of the three languages involved is effected by interlanguage comparisons. The article touches on the parts of speech, case and gender distinctions, word-order, etc, but the strong and weak points of Sterpin’s contrastive-polyglot approach are best studied in his survey of English speech-sounds. Sterpin is sparing in his use of illustrative examples, the parallels he draws are not free from ambiguity, and his sound descriptions suffer from an imperfect understanding of the organs of speech. On the other hand, he shows practical skill in tongues, and his transliterations and ‘names’ of the letters of the four alphabets are no less ingenious than the contrastive layout as a whole. Especially helpful is a table of ‘diphthongues’ and ‘triphthongues’ on the basis of which it has been possible to assign the English long vowels their relative position in the vowel tract. In addition, there are comments on vowels in weak position and on consonants.

scholarly journals XXVI.—On the Fossil Flora of the South Wales Coal Field, and the Relationship of its Strata to the Somerset and Bristol Coal Field

1895 ◽  
Vol 37 (3) ◽  
pp. 565-614 ◽  
Author(s):  
Robert Kidston
Keyword(s):  
Relative Position ◽  
The Other ◽  
Fossil Flora ◽  
Coal Field ◽  
The South ◽  
White Ash ◽  
South Wales ◽  
Relationship Of ◽  
Coal Measures ◽  
The Relationship

The Coal Measures of the South Wales Coal Field fall into three well-marked divisions:—I. The Upper Pennant or Upper Penllergare Series.II. The Lower Pennant Series.III. The White Ash Series.In 1885 I paid a visit to this Coal Field, with the object of studying its Fossil Flora, hoping by this means to ascertain the relative position of the Welsh Coal Measures to those of the other Coal Fields of Britain.

Poggendorff Illusion as a Function of Orientation of Transversal and Parallel Lines

1976 ◽  
Vol 43 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Barry S. Anton
Keyword(s):  
Visual Acuity ◽  
Line Segment ◽  
Poggendorff Illusion ◽  
Human Subjects ◽  
Parallel Line ◽  
Normal Vision ◽  
Transversal Line ◽  
Line Segments ◽  
Adult Human ◽  
Parallel Lines

Adult human subjects (8 male, 8 female undergraduates) with normal vision were required to judge various orientations of the Poggendorff illusion. The transversal and parallel line-segments of the illusion were manipulated to produce the orientations to be judged. Minimum illusion occurred when the transversal line-segment was oriented 90° with respect to true vertical or true horizontal. Magnitude of illusion increased as the transversal line-segment deviated from these positions. The findings suggested that there is a stability of horizontal and vertical orientations. In addition, the hypothesis that visual acuity plays a role in the perception of the Poggendorff illusion was proposed.

The Oblique Line Illusion: The Poggendorff Effect without Parallels

1973 ◽  
Vol 25 (4) ◽  
pp. 535-541 ◽  
Author(s):  
R. H. Day
Keyword(s):  
Oblique Line ◽  
Median Plane ◽  
Poggendorff Figure ◽  
Poggendorff Effect

The apparent misalignment of two oblique collinear lines was investigated in two experiments. In the first the effect with the lines at 45° to the median plane was compared with that for the same two lines separated by the conventional parallels of the Poggendorff figure. The illusion with the two lines was consistent and significant but about one-third the magnitude of that with the parallels. The two illusions were significantly correlated. In the second experiment the angle of the two oblique, collinear lines was varied in 15° steps. The misalignment illusion was maximal at 45° and smaller but significant at 60 and 75°. There was no significant effect at 15 and 30°.

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